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Old 01-13-2012, 06:35 PM   #1
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testing circuit breakers in old house


to see if they trip.

Is it prudent to test thet CBs in an old house to make such they trip when overcurrent?

I have a small load center (for two CBs). I can use it to test the CBs of the old house I just bought (pushmatics bulldog).

I will put a CB rate one size higher in the small load center and then short the circuit with the CB to be tested in series. The larger CB will protect gross overcurrent while allowing the smaller CB to be tested to make sure it does trip.

Good idea?

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Old 01-13-2012, 06:39 PM   #2
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testing circuit breakers in old house


Well........

It sounds more controlled than sticking 2 ice-picks in a receptacle and crossing them.

Good idea? I dunno if I'd go that far.

What makes you think they are bad?

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Old 01-13-2012, 06:43 PM   #3
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testing circuit breakers in old house


I agree, what would make you even think of doing that?
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Old 01-13-2012, 07:21 PM   #4
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testing circuit breakers in old house


The only way to certify that a breaker will work as it was intended, is to have someone with the proper equipment do so, and then they have to tag it as being tested on such and such date, their initials. Otherwise, if the breakers are over a certain age (more than 30 years), suggest replacing them with new ones, along with either cleaning up the bus bar's, which have to be done while no power going to the panel, along with applying no-ox to the aluminum tails and then re-torquing the connections.

And why in the world did you split this particular question off of the original topic? Is there something else unrelated, which you would like to know, that is not related to the original question.
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Old 01-13-2012, 07:32 PM   #5
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testing circuit breakers in old house


Quote:
And why in the world did you split this particular question off of the original topic? Is there something else unrelated, which you would like to know, that is not related to the original question.
I get the feeling I'm missing something. Another related thread?
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Old 01-13-2012, 07:35 PM   #6
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testing circuit breakers in old house


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I get the feeling I'm missing something. Another related thread?
Bull Dog Pushmatic Electrical panel and Circuit Breakers
This one maybe not so much Investigating grounding for an older house
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Old 01-13-2012, 07:59 PM   #7
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testing circuit breakers in old house


We do NOT test residential breakers. We replace them. End of story.
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Old 01-13-2012, 09:22 PM   #8
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testing circuit breakers in old house


Shorting is not a proper test anyway. You need to overload it to a specified over current and then if it trips.
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Old 01-13-2012, 09:36 PM   #9
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testing circuit breakers in old house


Circuit breakers...like everything else has only so long of useful life span. If these breakers are old enough for you to question their integrity you should change them out.
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Old 01-13-2012, 09:54 PM   #10
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testing circuit breakers in old house


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Shorting is not a proper test anyway. You need to overload it to a specified over current and then if it trips.
Come on. You take all of the fun out of it. It is even more fun watching someone drop a Crescent wrench on a 1200 amp battery bank. Talk about watching someone piss their pants, and of course it is not me.
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Old 01-13-2012, 10:02 PM   #11
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testing circuit breakers in old house


Testing a circuit breaker at its rated voltage is a really bad idea.

Most manufacturers recommend (but do not require) that breakers be replaced if they have tripped on a short circuit. This is because after interrupting a large current at rated voltage, the contacts will become pitted and coated with copper oxide, which does not conduct well. The end result will likely be a failure at some later point, the failure could very well damage the bus that the breaker connects to.

All breakers can be tested with the proper equipment. But unless the breakers are extremely expensive or very difficult to obtain, replacement is by far the best option.

Testing a branch circuit breaker with a test set takes about 10-15 minutes each. That's pretty expensive compared to just replacing them.

The only times I've ever tested small breakers is for hospital certification, and a few industrial establishments require it.
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Old 01-13-2012, 11:14 PM   #12
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testing circuit breakers in old house


Testing any circuit breaker, with out a properly set up,
and safe enviroment, is just asking for trouble !
The chance of some one getting hurt is REAL !

For that reason alone most people would say
DONT DO IT !
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Old 01-15-2012, 07:35 PM   #13
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testing circuit breakers in old house


I'd replace that panel. Here's the reasons why:

1. The Pushmatic is a very old design, going back to the early 1950s. The older ones are a thermal-only type of breaker, lacking a magnetic trip mechanism. This means that it works acceptably at interrupting overloads, but if a short occurs, the thermal mechanism will be slow to activate, possibly too slow to prevent an arc or fire. Also, it's conceivable that, in a short circuit, the breaker's contacts might weld before the thermal trip mechanism activates. Apparently a magnetic mechanism was added to later models, but nobody is sure when.

2. The little flags that tell you the status of the breaker are known to fail over time, so it is often hard to tell if the breaker is on or off.

3. The internal mechanisms get very stiff. This makes the breaker hard to operate.

4. Replacement breakers are expensive and don't always fit older style panels.

Also, I've seen reports that in some parts of California, electricians have found Pushmatic panel installations where there is no main breaker; everything on the line side of the branch circuit breakers is unprotected. That's obviously not a fault of the panel itself, but it is an indication of how old some of these panels are, that they were able to get away with installing it that way.
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Old 01-15-2012, 07:38 PM   #14
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testing circuit breakers in old house


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Originally Posted by fa_f3_20 View Post

Also, I've seen reports that in some parts of California, electricians have found Pushmatic panel installations where there is no main breaker; everything on the line side of the branch circuit breakers is unprotected. That's obviously not a fault of the panel itself, but it is an indication of how old some of these panels are, that they were able to get away with installing it that way.
Those were split-buss panels. Most all manufacturers had them. They are nothing out of the ordinary for that vintage.
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Old 01-16-2012, 01:00 AM   #15
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testing circuit breakers in old house


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Those were split-buss panels. Most all manufacturers had them. They are nothing out of the ordinary for that vintage.
Could have been; what I said above was from a couple of Internet reports at Inspectapedia. The only Pushmatic panel I've ever seen in person was not a split bus; it had the main breaker in a separate box.

Incidentally, one cute thing about the Pushmatics was that at least some of them came with a set of stickers you could use to identify the breakers. They were pre-printed with commonly used designations like "stove", "heat", "dryer", "kitchen", "bedroom", "garage", etc. You just stuck them on the breaker handle.

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